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Petit G, Mencuccini M, Carrer M, Prendin AL, Hölttä T. Axial conduit widening, tree height, and height growth rate set the hydraulic transition of sapwood into heartwood. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5072-5087. [PMID: 37352139 DOI: 10.1093/jxb/erad227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/12/2023] [Indexed: 06/25/2023]
Abstract
The size-related xylem adjustments required to maintain a constant leaf-specific sapwood conductance (KLEAF) with increasing height (H) are still under discussion. Alternative hypotheses are that: (i) the conduit hydraulic diameter (Dh) at any position in the stem and/or (ii) the number of sapwood rings at stem base (NSWr) increase with H. In addition, (iii) reduced stem elongation (ΔH) increases the tip-to-base conductance through inner xylem rings, thus possibly the NSWr contributing to KLEAF. A detailed stem analysis showed that Dh increased with the distance from the ring apex (DCA) in all rings of a Picea abies and a Fagus sylvatica tree. Net of DCA effect, Dh did not increase with H. Using sapwood traits from a global dataset, NSWr increased with H, decreased with ΔH, and the mean sapwood ring width (SWrw) increased with ΔH. A numerical model based on anatomical patterns predicted the effects of H and ΔH on the conductance of inner xylem rings. Our results suggest that the sapwood/heartwood transition depends on both H and ΔH, and is set when the carbon allocation to maintenance respiration of living cells in inner sapwood rings produces a lower gain in total conductance than investing the same carbon in new vascular conduits.
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Affiliation(s)
- Giai Petit
- Università degli Studi di Padova, Dept. TeSAF, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Maurizio Mencuccini
- CREAF, Bellaterra (Cerdanyola del Vallès), E08193, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona, 08010, Spain
| | - Marco Carrer
- Università degli Studi di Padova, Dept. TeSAF, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Angela Luisa Prendin
- Università degli Studi di Padova, Dept. TeSAF, Viale dell'Università 16, 35020 Legnaro (PD), Italy
- Department of Biology, Ecoinformatics and Biodiversity, Aarhus University, Ny Munkegade 114-116, building 1540, 8000 Aarhus C, Denmark University of Aarhus, Denmark
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/ Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Latokartanonkaari 7, FI 00014 Helsinki, Finland
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2
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Hietz P, Rosner S, Scheicher K. The three-dimensional structure of wood enables horizontal water transport needed to conduct water around lesions. Sci Rep 2023; 13:15057. [PMID: 37699914 PMCID: PMC10497525 DOI: 10.1038/s41598-023-41817-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 08/31/2023] [Indexed: 09/14/2023] Open
Affiliation(s)
- Peter Hietz
- Institute of Botany, University of Natural Resources and Life Sciences, 1180, Vienna, Austria.
| | - Sabine Rosner
- Institute of Botany, University of Natural Resources and Life Sciences, 1180, Vienna, Austria
| | - Klaus Scheicher
- Institute of Mathematics, University of Natural Resources and Life Sciences, 1180, Vienna, Austria
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3
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Ma L, Meng Q, Jiang X, Ge Z, Cao Z, Wei Y, Jiao L, Yin Y, Guo J. Spatial organization and connectivity of wood rays in Pinus massoniana xylem based on high-resolution μCT-assisted network analysis. PLANTA 2023; 258:28. [PMID: 37358610 DOI: 10.1007/s00425-023-04185-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/15/2023] [Indexed: 06/27/2023]
Abstract
MAIN CONCLUSION Spatial organization and connectivity of wood rays in Pinus massoniana was comprehensively viewed and regarded as anatomical adaptions to ensure the properties of rays in xylem. Spatial organization and connectivity of wood rays are essential for understanding the wood hierarchical architecture, but the spatial information is ambiguous due to small cell size. Herein, 3D visualization of rays in Pinus massoniana was performed using high-resolution μCT. We found brick-shaped rays were 6.5% in volume fractions, nearly twice the area fractions estimated by 2D levels. Uniseriate rays became taller and wider during the transition from earlywood to latewood, which was mainly contributed from the height increment of ray tracheids and widened ray parenchyma cells. Furthermore, both volume and surface area of ray parenchyma cells were larger than ray tracheids, so ray parenchyma took a higher proportion in rays. Moreover, three different types of pits for connectivity were segmented and revealed. Pits in both axial tracheids and ray tracheids were bordered, but the pit volume and pit aperture of earlywood axial tracheids were almost tenfold and over fourfold larger than ray tracheids. Contrarily, cross-field pits between ray parenchyma and axial tracheids were window-like with the principal axis of 31.0 μm, but its pit volume was approximately one-third of axial tracheids. Additionally, spatial organization of rays and axial resin canal was analyzed by a curved surface reformation tool, providing the first evidence of rays close to epithelial cells inward through the resin canal. Epithelial cells had various morphologies and large variations in cell size. Our results give new insights into the organization of radial system of xylem, especially the connectivity of rays with adjacent cells.
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Affiliation(s)
- Lingyu Ma
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Qiulu Meng
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Xiaomei Jiang
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Zhedong Ge
- School of Information and Electrical Engineering, Shandong Jianzhu University, No.1000, Fengming Road, Lingang Development Zone, Jinan, 250101, Shandong, China
| | - Zixiong Cao
- Object Research Systems (ORS) Inc., 460 Ste-Catherine West, #600, Montreal, QC, H3B 1A7, Canada
| | - Yupei Wei
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Lichao Jiao
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Yafang Yin
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China
| | - Juan Guo
- Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing, 100091, China.
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Hydraulic Function Analysis of Conifer Xylem Based on a Model Incorporating Tracheids, Bordered Pits, and Cross-Field Pits. FORESTS 2022. [DOI: 10.3390/f13020171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Wood has a highly complex and anisotropic structure. Its xylem characteristics are key in determining the hydraulic properties of plants to transport water efficiently and safely, as well as the permeability in the process of wood impregnation modification. Previous studies on the relationship between the xylem structure and hydraulic conductivity of conifer have mainly focused on tracheids and bordered pits, with only a few focusing on the conduction model of cross-field pits which connect tracheids and rays. This study takes the xylem structure of conifer as an example, drawing an analogy between water flow under tension and electric current, and extends the model to the tissue scale, including cross-field pits by establishing isometric scaling. The structure parameters were collected by scanning electron microscopy and transmission electron microscopy. The improved model can quantify the important hydraulic functional characteristics of xylem only by measuring the more easily obtained tracheid section size. Then, this model was applied to quantify the relationship between the xylem anatomical structure and hydraulic properties in the pine (Pinus sylvestris L. var. mongholica Litv.) and the spruce (Picea koraiensis Nakai), and also to evaluate the effects of the number and size of cross-field pits on xylem conduction. The results showed that the growth ring conduction value of the pine was more than twice that of the spruce for the two tree species with similar growth widths in this study. The tracheid wall resistance of the pine reflected the result of the interaction of the size and number of cross-field pits, in comparison, the wall resistance of the spruce was more sensitive to the number of cross-field pits. Finally, the calculation output of the new model was cross-validated with the literature, which verified the accuracy and effectiveness of the model. This study provides an effective and complete solution for xylem conductivity measurement and the study of wood ecophysiological diversity and processing.
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Toumpanaki E, Shah DU, Eichhorn SJ. Beyond What Meets the Eye: Imaging and Imagining Wood Mechanical-Structural Properties. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2001613. [PMID: 32830395 DOI: 10.1002/adma.202001613] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/12/2020] [Indexed: 05/20/2023]
Abstract
Wood presents a hierarchical structure, containing features at all length scales: from the tracheids or vessels that make up its cellular structure, through to the microfibrils within the cell walls, down to the molecular architecture of the cellulose, lignin, and hemicelluloses that comprise its chemical makeup. This structure renders it with high mechanical (e.g., modulus and strength) and interesting physical (e.g., optical) properties. A better understanding of this structure, and how it plays a role in governing mechanical and other physical parameters, will help to better exploit this sustainable resource. Here, recent developments on the use of advanced imaging techniques for studying the structural properties of wood in relation to its mechanical properties are explored. The focus is on synchrotron nuclear magnetic resonance spectroscopy, X-ray diffraction, X-ray tomographical imaging, Raman and infrared spectroscopies, confocal microscopy, electron microscopy, and atomic force microscopy. Critical discussion on the role of imaging techniques and how fields are developing rapidly to incorporate both spatial and temporal ranges of analysis is presented.
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Affiliation(s)
- Eleni Toumpanaki
- Bristol Composites Institute, CAME School of Engineering, University of Bristol, University Walk, Bristol, BS8 1TR, UK
| | - Darshil U Shah
- Department of Architecture, Centre for Natural Materials Innovation, University of Cambridge, Cambridge, CB2 1PX, UK
| | - Stephen J Eichhorn
- Bristol Composites Institute, CAME School of Engineering, University of Bristol, University Walk, Bristol, BS8 1TR, UK
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Epron D, Kamakura M, Azuma W, Dannoura M, Kosugi Y. Diurnal variations in the thickness of the inner bark of tree trunks in relation to xylem water potential and phloem turgor. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2021; 2:112-124. [PMID: 37283860 PMCID: PMC10168075 DOI: 10.1002/pei3.10045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/03/2021] [Accepted: 04/07/2021] [Indexed: 06/08/2023]
Abstract
The inner bark plays important roles in tree stems, including radial exchange of water with the xylem and translocation of carbohydrates. Both processes affect the water content and the thickness of the inner bark on a diurnal basis. For the first time, we simultaneously measured the diurnal variations in the inner bark thickness of hinoki cypress (Chamaecyparis obtusa) by using point dendrometers and those of local xylem potential by using stem psychrometers located next to the dendrometers to determine how these variations were related to each other, to phloem turgor and carbohydrate transport. We also estimated the axial hydrostatic pressure gradient by measuring the osmolality of the sap extracted from the inner bark. The inner bark shrunk during the day and swelled during the night with an amplitude related to day-to-day and seasonal variations in climate. The relationship between changes in xylem water potential and inner bark thickness exhibited a hysteresis loop during the day with a median lag of 2 h. A phloem turgor-related signal can be retrieved from the diurnal variations in the inner bark thickness, which was higher at the upper than at the lower position along the trunk. However, a downward hydrostatic pressure gradient was only observed at dawn, suggesting diurnal variations in the phloem sap flow velocity.
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Affiliation(s)
- Daniel Epron
- Graduate School of AgricultureKyoto UniversityKyotoJapan
- AgroParisTechINRAEUMR SILVAUniversité de LorraineNancyFrance
| | - Mai Kamakura
- Graduate School of AgricultureKyoto UniversityKyotoJapan
| | - Wakana Azuma
- Graduate School of Agricultural ScienceKobe UniversityKobeJapan
| | | | - Yoshiko Kosugi
- Graduate School of AgricultureKyoto UniversityKyotoJapan
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Hammond WM, Johnson DM, Meinzer FC. A thin line between life and death: Radial sap flux failure signals trajectory to tree mortality. PLANT, CELL & ENVIRONMENT 2021; 44:1311-1314. [PMID: 33600002 DOI: 10.1111/pce.14033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Abstract
This article comments on: Seeking the "point of no return" in the sequence of events leading to mortality of mature trees.
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Affiliation(s)
- William M Hammond
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
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Preisler Y, Tatarinov F, Grünzweig JM, Yakir D. Seeking the "point of no return" in the sequence of events leading to mortality of mature trees. PLANT, CELL & ENVIRONMENT 2021; 44:1315-1328. [PMID: 33175417 DOI: 10.1111/pce.13942] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/03/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
Drought-related tree mortality is increasing globally, but the sequence of events leading to it remains poorly understood. To identify this sequence, we used a 2016 tree mortality event in a semi-arid pine forest where dendrometry and sap flow measurements were carried out in 31 trees, of which seven died. A comparative analysis revealed three stages leading to mortality. First, a decrease in tree diameter in all dying trees, but not in the surviving trees, 8 months "prior to the visual signs of mortality" (PVSM; e.g., near complete canopy browning). Second, a decay to near zero in the diurnal stem swelling/shrinkage dynamics, reflecting the loss of stem radial water flow in the dying trees, 6 months PVSM. Third, cessation of stem sap flow 3 months PVSM. Eventual mortality could therefore be detected long before visual signs were observed, and the three stages identified here demonstrated the differential effects of drought on stem growth, water storage capacity and soil water uptake. The results indicated that breakdown of stem radial water flow and phloem function is a critical element in defining the "point of no return" in the sequence of events leading to mortality of mature trees.
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Affiliation(s)
- Yakir Preisler
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
- Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Fedor Tatarinov
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
| | - José M Grünzweig
- Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Dan Yakir
- Earth and Planetary Science Department, Weizmann Institute of Science, Rehovot, Israel
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Kitin P, Nakaba S, Hunt CG, Lim S, Funada R. Direct fluorescence imaging of lignocellulosic and suberized cell walls in roots and stems. AOB PLANTS 2020; 12:plaa032. [PMID: 32793329 PMCID: PMC7415075 DOI: 10.1093/aobpla/plaa032] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/21/2020] [Indexed: 05/05/2023]
Abstract
Investigating plant structure is fundamental in botanical science and provides crucial knowledge for the theories of plant evolution, ecophysiology and for the biotechnological practices. Modern plant anatomy often targets the formation, localization and characterization of cellulosic, lignified or suberized cell walls. While classical methods developed in the 1960s are still popular, recent innovations in tissue preparation, fluorescence staining and microscopy equipment offer advantages to the traditional practices for investigation of the complex lignocellulosic walls. Our goal is to enhance the productivity and quality of microscopy work by focusing on quick and cost-effective preparation of thick sections or plant specimen surfaces and efficient use of direct fluorescent stains. We discuss popular histochemical microscopy techniques for visualization of cell walls, such as autofluorescence or staining with calcofluor, Congo red (CR), fluorol yellow (FY) and safranin, and provide detailed descriptions of our own approaches and protocols. Autofluorescence of lignin in combination with CR and FY staining can clearly differentiate between lignified, suberized and unlignified cell walls in root and stem tissues. Glycerol can serve as an effective clearing medium as well as the carrier of FY for staining of suberin and lipids allowing for observation of thick histological preparations. Three-dimensional (3D) imaging of all cell types together with chemical information by wide-field fluorescence or confocal laser scanning microscopy (CLSM) was achieved.
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Affiliation(s)
- Peter Kitin
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, USA
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan
| | - Satoshi Nakaba
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan
| | | | - Sierin Lim
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore
| | - Ryo Funada
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan
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10
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Abstract
Research Highlights: Pronounced winter embolism and recovery were observed in the Alpine conifer shrub Pinus mugo L. Data indicated that the hydraulic courses and underlying mechanism were similar to timberline trees. Background and Objectives: At high elevation, plants above the snow cover are exposed to frost drought and temperature stress during winter. Previous studies demonstrated winter stress to induce low water potentials (Ψ) and significant xylem embolism (loss of conductivity, or LC) in evergreen conifer trees, and recovery from embolism in late winter. Here, we analyzed xylem hydraulics and related structural and cellular changes in a conifer shrub species. Materials and Methods: The uppermost branches of Pinus mugo shrubs growing at the Alpine timberline were harvested over one year, and the Ψ, water content, LC, proportion of aspirated pits, and carbohydrate contents were analyzed. Results: Minimum Ψ (−1.82 ± 0.04 MPa) and maximum LC (39.9% ± 14.5%) values were observed in mid and late winter, followed by a recovery phase. The proportion of aspirated pits was also highest in winter (64.7% ± 6.9% in earlywood, 27.0% ± 1.4% in latewood), and decreased in parallel with hydraulic recovery in late winter and spring. Glucose and fructose contents gradually decreased over the year, while starch contents (also microscopically visible as starch grains in needle and stem tissues) increased from May to July. Conclusions: The formation and recovery of embolism in Pinus mugo were similar to those of timberline trees, as were the underlying mechanisms, with pit aspiration enabling the isolation of embolized tracheids, and changes in carbohydrate contents indicating adjustments of osmotic driving forces for water re-distribution. The effects of future changes in snow cover regimes may have pronounced and complex effects on shrub-like growth forms, because a reduced snow cover may shorten the duration of frost drought, but expose the plants to increased temperature stress and impair recovery processes.
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11
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Ogasa MY, Taneda H, Ooeda H, Ohtsuka A, Maruta E. Repair of severe winter xylem embolism supports summer water transport and carbon gain in flagged crowns of the subalpine conifer Abies veitchii. TREE PHYSIOLOGY 2019; 39:1725-1735. [PMID: 31211390 DOI: 10.1093/treephys/tpz066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 02/15/2019] [Accepted: 05/20/2019] [Indexed: 06/09/2023]
Abstract
Xylem embolism induced by winter drought is a serious dysfunction in evergreen conifers growing at wind-exposed sites in the mountains. Some coniferous species can recover from winter embolism. The aim of this study was to determine whether wind direction influences embolism formation and/or repair dynamics on short windward and long leeward branches of asymmetrical `flagged' crowns. We analyzed the effect of branch orientation on percentage loss of xylem conductive area (PLC), leaf functional traits and the xylem:leaf area ratio for subalpine, wind-exposed flagged-crown Abies veitchii trees in the northern Yatsugatake Mountains of central Japan. In late winter, the shoot water potential was below -2.5 MPa, and the PLC exceeded 80% in 2-year-old branches, independent of branch orientation within a flagged crown. Both of these parameters almost fully recovered by summer. At branch internodes 4 years of age and older, seasonal changes in PLC were not found in either windward or leeward branches, but the PLC was higher in less leafy windward branches. The leaf nitrogen content and water-use efficiency of mature leaves were comparable between windward branches and leafy leeward branches. The ratio of xylem conductive area to total leaf area was the same for windward and leeward branches. These results indicate that the repair of winter xylem embolism allows leaf physiological functions to be maintained under sufficient leaf water supply, even on winter-wind-exposed branches. This permits substantial photosynthetic carbon gain during the following growing season on both windward and leeward branches. Thus, xylem recovery from winter embolism is a key trait for the survival of harsh winters and to support productivity on the individual level in flagged-crown A. veitchii trees.
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Affiliation(s)
- Mayumi Y Ogasa
- Department of Plant Ecology, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
- Forest Ecology Group, Kansai Research Center, Forestry and Forest Products Research Institute, 68 Nagaikyutaroh, Momoyama-choh, Fushimi-ku, Kyoto, Kyoto 612-0855, Japan
| | - Haruhiko Taneda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroki Ooeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Simplex Inc., 1-23-1 Toranomon, Minato-ku, Tokyo 105-6319, Japan
| | - Akihiro Ohtsuka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Asahi Kasei Corp., 1-105 Kandajimbochoh, Chiyoda-ku, Tokyo 100-8550, Japan; orcid.org/0000-0002-3814-4937
| | - Emiko Maruta
- Department of Biological Sciences, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
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Copini P, Vergeldt FJ, Fonti P, Sass-Klaassen U, den Ouden J, Sterck F, Decuyper M, Gerkema E, Windt CW, Van As H. Magnetic resonance imaging suggests functional role of previous year vessels and fibres in ring-porous sap flow resumption. TREE PHYSIOLOGY 2019; 39:1009-1018. [PMID: 30896019 DOI: 10.1093/treephys/tpz019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/15/2019] [Indexed: 06/09/2023]
Abstract
Reactivation of axial water flow in ring-porous species is a complex process related to stem water content and developmental stage of both earlywood-vessel and leaf formation. Yet empirical evidence with non-destructive methods on the dynamics of water flow resumption in relation to these mechanisms is lacking. Here we combined in vivo magnetic resonance imaging and wood-anatomical observations to monitor the dynamic changes in stem water content and flow during spring reactivation in 4-year-old pedunculate oaks (Quercus robur L.) saplings. We found that previous year latewood vessels and current year developing earlywood vessels form a functional unit for water flow during growth resumption. During spring reactivation, water flow shifted from latewood towards the new earlywood, paralleling the formation of earlywood vessels and leaves. At leaves' full expansion, volumetric water content of previous rings drastically decreased due to the near-absence of water in fibre tissue. We conclude (i) that in ring-porous oak, latewood vessels play an important hydraulic role for bridging the transition between old and new water-conducting vessels and (ii) that fibre and parenchyma provides a place for water storage.
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Affiliation(s)
- Paul Copini
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
- Wageningen Environmental Research, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
| | - Frank J Vergeldt
- Laboratory of Biophysics and MAGNetic resonance research FacilitY (MAGNEFY), Wageningen University & Research, Postbus 8128, 6700ET Wageningen, The Netherlands
| | - Patrick Fonti
- Swiss Federal Institute for Forest Snow and Landscape Research WSL, CH-8903 Birmensdorf, Switzerland
| | - Ute Sass-Klaassen
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
| | - Jan den Ouden
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
| | - Mathieu Decuyper
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
- Laboratory of Geo-Information Science and Remote Sensing, Wageningen University & Research, PO Box 47, AA Wageningen, The Netherlands
| | - Edo Gerkema
- Laboratory of Biophysics and MAGNetic resonance research FacilitY (MAGNEFY), Wageningen University & Research, Postbus 8128, 6700ET Wageningen, The Netherlands
| | - Carel W Windt
- IBG-2: Plant Sciences, Institute of Bio- and Geosciences, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Henk Van As
- Laboratory of Biophysics and MAGNetic resonance research FacilitY (MAGNEFY), Wageningen University & Research, Postbus 8128, 6700ET Wageningen, The Netherlands
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13
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Lehnebach R, Beyer R, Letort V, Heuret P. The pipe model theory half a century on: a review. ANNALS OF BOTANY 2018; 121:773-795. [PMID: 29370362 PMCID: PMC5906905 DOI: 10.1093/aob/mcx194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 11/28/2017] [Indexed: 05/12/2023]
Abstract
Background More than a half century ago, Shinozaki et al. (Shinozaki K, Yoda K, Hozumi K, Kira T. 1964a. A quantitative analysis of plant form - the pipe model theory. I. Basic analyses. Japanese Journal of Ecology B: 97-105) proposed an elegant conceptual framework, the pipe model theory (PMT), to interpret the observed linear relationship between the amount of stem tissue and corresponding supported leaves. The PMT brought a satisfactory answer to two vividly debated problems that were unresolved at the moment of its publication: (1) What determines tree form and which rules drive biomass allocation to the foliar versus stem compartments in plants? (2) How can foliar area or mass in an individual plant, in a stand or at even larger scales be estimated? Since its initial formulation, the PMT has been reinterpreted and used in applications, and has undoubtedly become an important milestone in the mathematical interpretation of plant form and functioning. Scope This article aims to review the PMT by going back to its initial formulation, stating its explicit and implicit properties and discussing them in the light of current biological knowledge and experimental evidence in order to identify the validity and range of applicability of the theory. We also discuss the use of the theory in tree biomechanics and hydraulics as well as in functional-structural plant modelling. Conclusions Scrutinizing the PMT in the light of modern biological knowledge revealed that most of its properties are not valid as a general rule. The hydraulic framework derived from the PMT has attracted much more attention than its mechanical counterpart and implies that only the conductive portion of a stem cross-section should be proportional to the supported foliage amount rather than the whole of it. The facts that this conductive portion is experimentally difficult to measure and varies with environmental conditions and tree ontogeny might cause the commonly reported non-linear relationships between foliage and stem metrics. Nevertheless, the PMT can still be considered as a portfolio of properties providing a unified framework to integrate and analyse functional-structural relationships.
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Affiliation(s)
- Romain Lehnebach
- Centre de coopération Internationale de la Recherche Agronomique pour le Développement (CIRAD), UMR Amap, Kourou, France
- Botany and Modelling of Plant Architecture and Vegetation (Amap), Université Montpellier, CIRAD, CNRS, INRA, IRD, Montpellier, France
| | - Robert Beyer
- Laboratory of Mathematics in Interaction with Computer Science (MICS), CentraleSupélec, France
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Véronique Letort
- Laboratory of Mathematics in Interaction with Computer Science (MICS), CentraleSupélec, France
| | - Patrick Heuret
- Institut National de la Recherche Agronomique (INRA), UMR Ecofog, Kourou, France
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Secchi F, Pagliarani C, Zwieniecki MA. The functional role of xylem parenchyma cells and aquaporins during recovery from severe water stress. PLANT, CELL & ENVIRONMENT 2017; 40:858-871. [PMID: 27628165 DOI: 10.1111/pce.12831] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/09/2016] [Accepted: 08/27/2016] [Indexed: 05/05/2023]
Abstract
Xylem parenchyma cells [vessel associated cells (VACs)] constitute a significant fraction of the xylem in woody plants. These cells are often closely connected with xylem vessels or tracheids via simple pores (remnants of plasmodesmata fields). The close contact and biological activity of VACs during times of severe water stress and recovery from stress suggest that they are involved in the maintenance of xylem transport capacity and responsible for the restoration of vessel/tracheid functionality following embolism events. As recovery from embolism requires the transport of water across xylem parenchyma cell membranes, an understanding of stem-specific aquaporin expression patterns, localization and activity is a crucial part of any biological model dealing with embolism recovery processes in woody plants. In this review, we provide a short overview of xylem parenchyma cell biology with a special focus on aquaporins. In particular we address their distributions and activity during the development of drought stress, during the formation of embolism and the subsequent recovery from stress that may result in refilling. Complemented by the current biological model of parenchyma cell function during recovery from stress, this overview highlights recent breakthroughs on the unique ability of long-lived perennial plants to undergo cycles of embolism-recovery related to drought/rewetting or freeze/thaw events.
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Affiliation(s)
- Francesca Secchi
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Turin, Grugliasco, 10095, Italy
| | - Chiara Pagliarani
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Turin, Grugliasco, 10095, Italy
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von Arx G, Arzac A, Olano JM, Fonti P. Assessing Conifer Ray Parenchyma for Ecological Studies: Pitfalls and Guidelines. FRONTIERS IN PLANT SCIENCE 2015; 6:1016. [PMID: 26635842 PMCID: PMC4649045 DOI: 10.3389/fpls.2015.01016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/03/2015] [Indexed: 05/09/2023]
Abstract
Ray parenchyma is an essential tissue for tree functioning and survival. This living tissue plays a major role for storage and transport of water, nutrients, and non-structural carbohydrates (NSC), thus regulating xylem hydraulics and growth. However, despite the importance of rays for tree carbon and water relations, methodological challenges hamper knowledge about ray intra- and inter-tree variability and its ecological meaning. In this study we provide a methodological toolbox for soundly quantifying spatial and temporal variability of different ray features. Anatomical ray features were surveyed in different cutting planes (cross-sectional, tangential, and radial) using quantitative image analysis on stem-wood micro-sections sampled from 41 mature Scots pines (Pinus sylvestris). The percentage of ray surface (PERPAR), a proxy for ray volume, was compared among cutting planes and between early- and latewood to assess measurement-induced variability. Different tangential ray metrics were correlated to assess their similarities. The accuracy of cross-sectional and tangential measurements for PERPAR estimates as a function of number of samples and the measured wood surface was assessed using bootstrapping statistical technique. Tangential sections offered the best 3D insight of ray integration into the xylem and provided the most accurate estimates of PERPAR, with 10 samples of 4 mm(2) showing an estimate within ±6.0% of the true mean PERPAR (relative 95% confidence interval, CI95), and 20 samples of 4 mm(2) showing a CI95 of ±4.3%. Cross-sections were most efficient for establishment of time series, and facilitated comparisons with other widely used xylem anatomical features. Earlywood had significantly lower PERPAR (5.77 vs. 6.18%) and marginally fewer initiating rays than latewood. In comparison to tangential sections, PERPAR was systematically overestimated (6.50 vs. 4.92%) and required approximately twice the sample area for similar accuracy. Radial cuttings provided the least accurate PERPAR estimates. This evaluation of ray parenchyma in conifers and the presented guidelines regarding data accuracy as a function of measured wood surface and number of samples represent an important methodological reference for ray quantification, which will ultimately improve the understanding of the fundamental role of ray parenchyma tissue for the performance and survival of trees growing in stressed environments.
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Affiliation(s)
- Georg von Arx
- Landscape Dynamics Research Unit, Swiss Federal Institute for Forest, Snow and Landscape Research WSLBirmensdorf, Switzerland
| | - Alberto Arzac
- Departamento de Biología Vegetal y Ecología, Facultad de Ciencia y Tecnología, Universidad del País VascoLeioa, Spain
| | - José M. Olano
- Departamento de Ciencias Agroforestales, Escuela Universitaria de Ingenierías Agrarias, Instituto Universitario de Investigación en Gestión Forestal Sostenible-Universidad de ValladolidSoria, Spain
| | - Patrick Fonti
- Landscape Dynamics Research Unit, Swiss Federal Institute for Forest, Snow and Landscape Research WSLBirmensdorf, Switzerland
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Pfautsch S, Hölttä T, Mencuccini M. Hydraulic functioning of tree stems--fusing ray anatomy, radial transfer and capacitance. TREE PHYSIOLOGY 2015; 35:706-22. [PMID: 26163488 DOI: 10.1093/treephys/tpv058] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/20/2015] [Indexed: 05/11/2023]
Abstract
Not long ago, textbooks on plant physiology divulged the view that phloem and xylem are separate transport systems with exclusive functions. Phloem was flowing downwards providing roots with carbohydrates. Xylem transported water upwards from roots to leaves. This simplified view has changed forever. Today we have a much-refined understanding of the complex transport mechanisms, regulatory functions and surprisingly ingenuous solutions trees have evolved to distribute carbohydrates and water internally to fuel growth and help mediate biotic and abiotic stresses. This review focuses on functional links between tissues of the inner bark region (i.e., more than just phloem) and the xylem, facilitated by radially aligned and interconnected parenchyma cells, called rays. Rays are usually found along the entire vertical axis of tree stems, mediating a number of transport processes. We use a top-down approach to unveil the role of rays in these processes. Due to the central role of rays in facilitating the coupling of inner bark and xylem we dedicate the first section to ray anatomy, pathways and control mechanisms involved in radial transport. In the second section, basic concepts and models for radial movement through rays are introduced and their impacts on water and carbon fluxes at the whole-tree level are discussed. This section is followed by a closer look at the capacitive function of composite tissues in stems where gradual changes in water potential generate a diurnal 'pulse'. We explain how this pulse can be measured and interpreted, and where the limitations of such analyses are. Towards the end of this review, we include a brief description of the role of radial transport during limited availability of water. By elucidating the strong hydraulic link between inner bark and xylem, the traditional view of two separate transport systems dissolves and the idea of one interconnected, yet highly segregated transport network for carbohydrates and water arises.
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Affiliation(s)
- Sebastian Pfautsch
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia
| | - Teemu Hölttä
- Department of Forest Sciences, University of Helsinki, PO Box 27, FIN-00014, Finland
| | - Maurizio Mencuccini
- School of Geo-Science, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN, UK ICREA at CREAF, Campus de UAB, Cerdanyola del Valles 08023, Barcelona, Spain
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Jupa R, Didi V, Hejátko J, Gloser V. An improved method for the visualization of conductive vessels in Arabidopsis thaliana inflorescence stems. FRONTIERS IN PLANT SCIENCE 2015; 6:211. [PMID: 25914701 PMCID: PMC4391271 DOI: 10.3389/fpls.2015.00211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/16/2015] [Indexed: 06/04/2023]
Abstract
Dye perfusion is commonly used for the identification of conductive elements important for the study of xylem development as well as precise hydraulic estimations. The tiny size of inflorescence stems, the small amount of vessels in close arrangement, and high hydraulic resistivity delimit the use of the method for quantification of the water conductivity of Arabidopsis thaliana, one of the recently most extensively used plant models. Here, we present an extensive adjustment to the method in order to reliably identify individual functional (conductive) vessels. Segments of inflorescence stems were sealed in silicone tubes to prevent damage and perfused with a dye solution. Our results showed that dyes often used for staining functional xylem elements (safranin, fuchsine, toluidine blue) failed with Arabidopsis. In contrast, Fluorescent Brightener 28 dye solution perfused through segments stained secondary cell walls of functional vessels, which were clearly distinguishable in native cross sections. When compared to identification based on the degree of development of secondary cell walls, identification with the help of dye perfusion revealed a significantly lower number of functional vessels and values of theoretical hydraulic conductivity. We found that lignified but not yet functional vessels form a substantial portion of the xylem in apical and basal segments of Arabidopsis and, thus, significantly affect the analyzed functional parameters of xylem. The presented methodology enables reliable identification of individual functional vessels, allowing thus estimations of hydraulic conductivities to be improved, size distributions and vessel diameters to be refined, and data variability generally to be reduced.
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Affiliation(s)
- Radek Jupa
- Department of Experimental Biology, Faculty of Science, Masaryk UniversityBrno, Czech Republic
| | - Vojtěch Didi
- Functional Genomics and Proteomics of Plants, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
| | - Jan Hejátko
- Functional Genomics and Proteomics of Plants, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
| | - Vít Gloser
- Department of Experimental Biology, Faculty of Science, Masaryk UniversityBrno, Czech Republic
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Spicer R. Symplasmic networks in secondary vascular tissues: parenchyma distribution and activity supporting long-distance transport. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:1829-48. [PMID: 24453225 DOI: 10.1093/jxb/ert459] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Stems that develop secondary vascular tissue (i.e. xylem and phloem derived from the vascular cambium) have unique demands on transport owing to their mass and longevity. Transport of water and assimilates must occur over long distances, while the increasing physical separation of xylem and phloem requires radial transport. Developing secondary tissue is itself a strong sink positioned between xylem and phloem along the entire length of the stem, and the integrity of these transport tissues must be maintained and protected for years if not decades. Parenchyma cells form an interconnected three-dimensional lattice throughout secondary xylem and phloem and perform critical roles in all of these tasks, yet our understanding of their physiology, the nature of their symplasmic connections, and their activity at the symplast-apoplast interface is very limited. This review highlights key historical work as well as current research on the structure and function of parenchyma in secondary vascular tissue in the hopes of spurring renewed interest in this area, which has important implications for whole-plant transport processes and resource partitioning.
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Affiliation(s)
- Rachel Spicer
- Department of Botany, Connecticut College, New London, CT 06320, USA
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Mayr S, Schmid P, Laur J, Rosner S, Charra-Vaskou K, Dämon B, Hacke UG. Uptake of water via branches helps timberline conifers refill embolized xylem in late winter. PLANT PHYSIOLOGY 2014; 164:1731-40. [PMID: 24521876 PMCID: PMC3982737 DOI: 10.1104/pp.114.236646] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Xylem embolism is a limiting factor for woody species worldwide. Conifers at the alpine timberline are exposed to drought and freeze-thaw stress during winter, which induce potentially lethal embolism. Previous studies indicated that timberline trees survive by xylem refilling. In this study on Picea abies, refilling was monitored during winter and spring seasons and analyzed in the laboratory and in situ experiments, based on hydraulic, anatomical, and histochemical methods. Refilling started in late winter, when the soil was frozen and soil water not available for the trees. Xylem embolism caused up to 86.2% ± 3.1% loss of conductivity and was correlated with the ratio of closed pits. Refilling of xylem as well as recovery in shoot conductance started in February and corresponded with starch accumulation in secondary phloem and in the mesophyll of needles, where we also observed increasing aquaporin densities in the phloem and endodermis. This indicates that active, cellular processes play a role for refilling even under winter conditions. As demonstrated by our experiments, water for refilling was thereby taken up via the branches, likely by foliar water uptake. Our results suggest that refilling is based on water shifts to embolized tracheids via intact xylem, phloem, and parenchyma, whereby aquaporins reduce resistances along the symplastic pathway and aspirated pits facilitate isolation of refilling tracheids. Refilling must be taken into account as a key process in plant hydraulics and in estimating future effects of climate change on forests and alpine tree ecosystems.
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Rosell JA, Gleason S, Méndez-Alonzo R, Chang Y, Westoby M. Bark functional ecology: evidence for tradeoffs, functional coordination, and environment producing bark diversity. THE NEW PHYTOLOGIST 2014; 201:486-497. [PMID: 24117609 DOI: 10.1111/nph.12541] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 09/04/2013] [Indexed: 05/08/2023]
Abstract
The causes underlying bark diversity are unclear. Variation has been frequently attributed to environmental differences across sites. However, variation may also result from tradeoffs and coordination between bark's multiple functions. Bark traits may also covary with wood and leaf traits as part of major dimensions of plant variation. To assess hypotheses regarding tradeoffs and functional coordination, we measured bark traits reflecting protection, storage, mechanics, and photosynthesis in branches of 90 species spanning a wide phylogenetic and environmental range. We also tested associations between bark, wood, and leaf traits. We partitioned trait variation within species, and within and across communities to quantify variation associated with across-site differences. We observed associations between bark mechanics and storage, density and thickness, and thickness and photosynthetic activity. Increasing bark thickness contributed significantly to stiffer stems and greater water storage. Bark density, water content, and mechanics covaried strongly with the equivalent wood traits, and to a lesser degree with leaf size, xylem conductivity, and vessel diameter. Most variation was observed within sites and had low phylogenetic signal. Compared with relatively minor across-site differences, tradeoffs and coordination among functions of bark, leaves, and wood are likely to be major and overlooked factors shaping bark ecology and evolution.
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Affiliation(s)
- Julieta A Rosell
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Sean Gleason
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Rodrigo Méndez-Alonzo
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Charles Young Drive S., Los Angeles, CA, 90095, USA
| | - Yvonne Chang
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Mark Westoby
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
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